This invention relates to a coloring method for synthetic resin articles without damaging actions on the resin surface of the article, such as swelling or melting. In general, the surface of synthetic resin articles is colored by painting, printing or dyeing. Another coloring method for synthetic resin is to scatter pigment into resin itself before forming. If we color resin by painting or printing, it becomes opaque and loses brightness and smoothness of the surface of resin. Since the surface of resin is swollen by dyeing, an after-treatment is required which takes a long time. In the dye dispersion method, color tone adjustment is often required while resin is in the raw state and it is rather difficult to get desired color or tone. According to this method, large amounts of raw resin must be treated at the same time from the economical point of view.